Field of the Invention
The present invention relates to a transparent display device.
Discussion of the Related Art
Recently, as society advances to the information-oriented society, the display field of processing and displaying a massive amount of information is rapidly advancing, and correspondingly, various flat panel display (FPD) devices have been developed and are attracting much attention. Examples of the FPD devices include LCD devices, plasma display panel (PDP) devices, field emission display (FED) devices, electroluminescence display (ELD) devices, organic light emitting diode (OLED) display devices, etc.
Recently, display devices are becoming miniaturized, light, and lowered in consumption power, and thus, the application fields of the display devices are continuously increasing. Particularly, in most electronic devices or mobile devices, a display device is used as a type of user interface.
Moreover, transparent display devices which enable a user to look at a background or an object located behind the transparent display devices are being actively researched recently. The transparent display devices are good in space availability, interior, and design and may be applied to various fields. The transparent display devices realize an information recognition function, an information processing function, and an information display function by using a transparent electronic device, thereby solving the spatial limitation and visual limitation of electronic devices. For example, a transparent display device may be applied to windows of buildings or vehicles and thus may be implemented as a smart window which allows a background to be seen or displays an image.
A transparent display device may be implemented as an organic light emitting display device. In this case, power consumption is small, but a contrast ratio is not changed in a dark environment and is reduced in an environment having light. A contrast ratio based on the dark environment may be defined as a dark room contrast ratio, and a contrast ratio based on the environment having light may be defined as a bright room contrast ratio. That is, the transparent display device includes a transmissive area in order for a user to look at a background or an object located behind the transparent display device, and for this reason, the bright room contrast ratio is reduced. Therefore, in a case where the transparent display device is implemented as an organic light emitting display device, a light control device that realizes a light shield mode for blocking light and a transmissive mode for transmitting light is needed for preventing the bright room contrast ratio from being reduced.
The light control device may include a first base film, a second base film, a liquid crystal layer that is in a liquid state and is disposed between the first base film and the second base film, and a plurality of partition walls for maintaining a constant gap of the liquid crystal layer. The partition walls may be disposed on the first base film and may be adhered to the second base film by an adhesive material which is provided on each of the partition walls. Therefore, the wider the area of each of the partition walls, the higher the adhesive force between the first base film and the second base film. Accordingly, each of the partition walls may have a certain area or more for maintaining the adhesive force between the first base film and the second base film at a certain level or more.
If the partition walls are formed of a transparent material, the partition walls cannot block light. Therefore, if the partition walls are disposed in an area corresponding to the transmissive area of the transparent display device, light leakage occurs in the partition walls in the light shield mode, and for this reason, a light shield rate is lowered. The partition walls may be formed of a light-absorbing material for preventing light leakage from occurring in the partition walls in the light shield mode. However, if the partition walls are disposed in the area corresponding to the transmissive area of the transparent display device, light is blocked by the partition walls in the transmissive mode, and for this reason, a light transmittance is lowered.